robertson



(No Model.) 4 Sheets-Sheet 1. I'. M. RGBERTSON.

EVAPORATING PAN.

No. 503,498. Patented Aug. 15, 1893.

(No Model.) l 4 sheets-sheen 2. F. M. ROBERTSON.

EVAPORATING PAN. No. 503,498. A Patented Aug. 15, 1893.

ywff d A @y (No Model.) 4 Sheets-Sheet 3.

P. M. ROBERTSON.' EVAPORATING PAN.

No. 503,498. Patented Aug. 15, 1893.

IIIv f i n UNITED STATES PATENT OFFICE.

FRANCIS M. ROBERTSON, OF FULHAM, ENGLAND.

EVAPO RATI NG- PAN.

SPECIFICATION forming part of Letters Patent No. 503,498, dated August 15, 1893.

Application lcd April 4, 1892. Serial No. I27,707. (No model.) Patented in Germany February 18, 1893, No. 67.182.

To all whom it may concern:

Be it known that I, FRANCIS MACDONALD ROBERTSON, gentleman, a subject of the Queen of Great Britain, residing at Fulham, in the county of Middlesex, England, have invented new and useful Improvements in Apparatus for Evaporating or Drying, (for which I have obtained Letters Patent in Germany, No. 67,182, dated February 18, 1893,) of which the following is a specification.

My said invention relates to improvements in apparatus for evaporating or drying liquid or semi-liquid materials and is suitable to be employed in the production of salt from brine or sea water, the production of sugar, and in connection with the condenser in distilling, in the manufacture of varnishes and colors, in the treatment of matter such as sewage, and for other uses.

In order that the said invention may be more clearly understood and readily carried into edect I will proceed, aided by the accompanying drawings, more fully to describe the same.

In the drawings: Figure l is an end elevation of an apparatus constructed according to my invention. Fig. 2 is a side elevation thereof. Fig. 3 is a longitudinal section taken on the line 3 8 of Fig. l. Fig. 4 is an end view of a similar apparatus representing a slight modification. Fig. 5 is a longitudinal section taken on the line 5-5 of Fig. 4. Fig. 6 is a longitudinal section, taken on the line 6-6 of Fig. 7, illustrating a further slight modification', and Fig. 7 is a transverse section taken on the line 7M? of Fig. 6.

Referring to Figs. l to 3, a represents a fixed cylindrical chamber which is formed of sheet copper, or other suitable material and which is heated from below by means of any suitable furnace, but I have not thought it necessary to show the latter. This chamber may be surroundedy by a steam, oil or water jacket for the purpose of bringing the material under treatment to or maintaining it at the requisite temperature, but as the nature of such jackets is well known, it is not considered necessary to illustrate the same.

The material to be treated is fed into the cylindrical chamber through a suitable feed opening, such as a', by the aid of any suitable conduct, aided if desired, by a screw or other conveyer, according to the consistency of the material, and the material may be either in a cold state, or it may be previously heated in any suitable manner according to its nature. The material is fed into the cylindrical chamber a until the latter is about a quarter full. The feed is then discontinued and a current of air, either in a natural condition or which has been previously dried or heated and which is forced or drawn by any suitable means enters the cylindrical chamber through the feed opening a', and passes continuously through the chamber a finding an exit by an exhaust opening a2, and, in its course, takes up the fluid or moisture within the cylindrical chamber a, as hereinafter more fully described.

Through the cent-er of the cylindrical chamber ct is passed a shaft b which is mounted in bearings b2 carried by transverse girders b3 and lubricated by means of oil feeders b4. This shaft b is driven by any suitable means such as a driving belt from a steam engine, or other source of power, and upon this shaft b, is fixed a continuous screw h' the blade of which is here shown with a plain surface, and the said blade is of such a diameter, as to closely fit the cylindrical chamber a. The screw b in the revolution of the shaft h constantly passes through the material under treatment, and thus takes up a portion thereof, and, on the continued revolution of the shaft b, the material so taken up is exposed to the current of air passing through the cylindrical chamber a, and the evaporation of the moisture is thus assisted, while, at the same time, the material under treatment is being moved forward.

To permit the return or circulation of the material moved forward by the screw IJ so that it is kept continuously in motion and caused to circulate from end to end of the cylindrical chamber a, until the completion of the process, I employ a device consisting of two tubular conduits a3 which are located upon the exterior of the cylindrical chamber a at each side and at the lower part thereof and communicate by ways at with the interior of the chamber a. By these means the material moved forward by the screw b will be caused to return by the conduits and then IOO forward again, and inasmuch as the tubular conduits cigare placed ator about a level with the bottom of the chamber ct no part of the material can escape the action of the screw b.

In the example given at Figs. 4. and 5 the tubular conruits a3 are fitted With screw conveyers @3X the threads of which are fox-ined Opposite to that of the scr-@W b', in order to maintain the circulation ofthe material under treatment, when through evaporation 0r otherwise, it is of such a consistency, that it will not readily tiow Without assistance. After the material has been subjected to the treatment above described for the requisite time to obtain the result desired, it may be removed from the apparatus through a door a5 provided for that purpose, or by other suitable means. A gage or bevel @5X is provided at the opposite end of the chamber c to indicate the level of the contents thereof. exhausting apparatus is in some cases, employed in connection with either of the openings d', a2, in order to assist the passage from the cylindrical chamber c of the current of i with, and in lieu thereof a cylinder ctx, the,

lower part of each end of which is left open, is arranged centrally within the chamber a scribed example, the screw b constantly moves the material forward through the cyll inder cx while such material returns along the sides and beneath the bottom thereof and I re-enters at the opposite end. Apparatus constructed in accordance with the modification lastly described will be found specially suitable for use in distilling operations.

lt is of importance that the blade of the. screw, tit, as hereinbefore stated, as closely as j the series of spaces above the surface of the t material being treated and between the upper or exposed portions of the convolutions of the screw blade. On the revolution of the Screw a quantity of the liquid or semi-liquid material under treatment will be thrown upward and outward thereby hermetically closing the space between the outer edge of the screw blade and the interior surface of the.

cylindrical chamber covering the latter at every revolution of the screw with a thin film of the material. As the current of air travels in a continuous stream through the chamber, it passes over the surface of the material being treated and is brought into contact with any material on the surface of the ever-changing exposed portions of the screw and on the interior surface of the cylindrical chamber and thereby effects the rapid evaporation of A blowing or the liquid or lmoisture at a comparatively low temperature.

By the employment of apparat us, construct ed in accordance with this invention 1n the manner hereinbefore described, I can evaporate Water or other liquid freely at a. lvv&r texnperature than boiling heat; and. at bo 111ng heat. much more rapidly, than bythe ordinary lnethods, the action of the revolving screw being to assist the passage of the current of air through the cylinder and to bring the air during its passage into such intimate contact with the liquid to be evaporated or material to be dried that evaporation takes place with great rapidity, the liquid to be evaporated or the material to be dried being constantly picked up by the blade or blades and thusa largely extended surface for evaporation 1s secured.

l have hereinbefore referred to the current of air being forced or drawn into and through the cylindrical chamber ct, but in places where there is hot and dry atmosphere I allow the screw b in the course of its revolutions to draw the same through the cylin drical chamber a.

l. An apparatus for evaporating or drying 4consisting of a closed chamber provided at and within this cylinder a-X works the screw b but otherwise the apparatus is similar tol that hereinbefore described. In this last deone end of its upper part with an inlet and at 'the opposite end with an outlet, a screw formed by a continuous blade located within such chamber and of such diameter as to lit as closely as possible therein but so as to be free to revolve and means for permitting the return of the material under treatment from the forward end of the chamber back to the initial end, substantially as herein shown and described.

2. The combination of the fixed cylindrical chamber having combined feed and air inlet a and exhaust opening a2 the transverse girders b3 having bearings b2, the shaft l) provided with a screw conveyer b and mounted in the bearings, a door through which the ma terial is removed, and a conduit connecting the ends of the cylindrical chamber; substantially as described.

3. The combination of the fixed cylindrical chamber having combined feed and air inlet a and exhaust opening c2 the transverse girders b3 having bearings b2, the shaft b provided with a screw conveyer b and mounted in the bearings, a door through which the material isl removed, and a conduit connecting the ends of the cylindrical chamber at the base thereof; substantially as described.

4. The combination of the fixed cylindrical chamber a, having combined feedand air inlet a', and exhaust opening a2, the transverse girders b3 having bearings b2 the shaft b provided with a screw conveyer b and mounted in the bearings, a door through which the materiall is removed, the two tubular conduits c3 located upon the exterior of the cylindrical chamber at each side and at the lower part thereof and the ways c4 connecting the cylin- ITO the cylindrical chamber at each side of the lower part thereof and the Ways d4 connecting the cylindrical chamber with the conduits; substantially as described.

F. M. ROBERTSON.

Witnesses:

W. S. MILLER, E. H. DAVIS, Both of 77 Gracechurch Street, London, E. C'. 

